You just bought a new digital SLR camera and you set out to take some great pitures only to be disappointed at the end results. What went wrong? The first thing you need to understand is how the camera works, captures light and stops motion. The answer is aperture and shutter speed, two of the most basic elements of photography. If you don't understand either of these functions it will be difficult for you to take good pictures.
Aperture
It's very simple; aperture is how your camera lens controls the light comming into the camera. Inside the lens there is an iris, just like in your eye, that opens and closes to different diameteres to allow the amount of light to enter the lens that you would like.
The amount of light that enters the camera changes as you change your camera's f-stop, which is the description of how much light is entering the camera at any time. A low f-stop value(f/1.5) means a greater diameter for your lenses iris which lets more light enter your camera. As a result, your picture will be brighter. A higer f-stop value (f/22) means a smaller diameter for your lenses iris which lets less light enter your camera.Thus, you have a darker picture.
As you change your f-stop from f/1.5 to f/22, each step will let in half the amount of light as the previous step. Conversely, if you open your lens one f-stop at a time (moving from f/22 to f/1.5), each step lets in twice the amount of light as before. So for example, if you move from f/5.6 to f/8, then you're going to let in half as much light. If you're going from f/8 to f5.6, you're going to let in twice as much light.
Different effects can be achieved by adjusting your f-stop, the most obvious effect being the brightness of your picture. Lowering the f-stop value will achieve a more shallow depth of field. This effect will isolate your subject by blurring your background. With a higher f-stops value like f/22, you get the greatest depth of field, so the entire picture is in focus. This effect works well for landscapes and scenic views. Varying your f-stop will vary your depth of field so don't be affraid to experiment. Take the same picture several times, changing your f-stop for each picture, then compare all the pictures. This is the best way to learn how f-stops work. Experiment and have fun with it. If you don't like what you see, just delete the pictures and try again.
Shutter Speed
Shutter speed is how your camera controls the amount of time your film or digital sensor is exposed to light. It regulates in seconds how long your camera's shutter is open. The exposure of your picture is directly proportional to the amount of time your digital sensor or film is exposed to light.
Slow shutter speeds of 1 second or longer, results in the camera lens being opened longer, allowing more light to enter the camera. Slower shutter speeds are used in low light situations or when you're trying to show the effects of speed like a race car. When using slower shutter speeds, you will need to use a tripod to reduce camera shake which will cause a blurry image.
Fast shutter speeds 1/1000 seconds, results in the camera lens being opened for a shorter amount of time, allowing less light to enter the camera. Fast shutter speeds are typically used for shooting clean, sharp, photographs and stopping motion.
Just like aperture, as you click through shutter speed stops, the light entering the camera doubles or becomes half as great. Speeds of 1/4 of a second to 1/2 of a second, lets in twice as much light. Going from 1/2 of a second to 1/4 of a second, lets in half as much light.
A rule of thumb for different shutter speeds and lenses is that the slowest shutter speed used without much blur from camera shake, is the shutter speed numerically closest to the lenses focal length or smaller. For example, if you are shooting with your lens at a focal length of 30mm, you should use a shutter speed of 1/30 of a second or less to ensure less blurry photographs.
Aperture and Shutter Speed Working Together
Shutter speed and aperture go hand in hand when shooting pictures. A fast shutter speed (1/1000 seconds) requires more light and a smaller f-stop value(f/1.5), to get the best exposure. If you use a fast shutter speed and a large f-stop, your picture will come out either too dark or completely black.
A slow shutter speed (1s) requires a lot less light and a larger f-stop value (f22) to get the best exposure. If you use slow shutter speed and a low f-stop value, your picture will come out either too bright or completely white.
In summary: slow shutter speeds use higher f- stops. Fast shutter speeds use lower f-stops.
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